Prognostic marker microRNA-125b inhibits tumorigenic properties of hepatocellular carcinoma cells via suppressing tumorigenic molecule eIF5A2.

Background: MicroRNAs (miRNAs) belong to a group of small non-coding RNA with differential expression in tumors, including hepatocellular carcinoma (HCC).

Aim: This study investigates the involvement of miR-125b in HCC.

Methods: Clinical analysis of miR-125b was performed using data derived from miRNA profiling and qPCR. Phenotypic changes of liver cell lines were examined after ectopic miR-125b expression. Lastly, bioinformatics analysis coupled with luciferase reporter assay was used to reveal the cellular target of miR-125b.

Results: A down-regulation of miR-125b was found in HCC tumors and cultured cells. Patients having tumors with ≥twofold reduction in miR-125b compared to adjacent non-tumor tissues contributed to 23 out of 49 HCC cases (46.9 %), while this down-regulation was usually found in patients with tumor venous infiltration and recurrence. miR-125b expression was also negatively correlated with increased serum AFP level and poor overall survival of patients. Ectopic expression of miR-125b led to alleviated tumor phenotypes of HCC cells. Among the 110 bioinformatically predicated candidates, 31 of them negatively correlated with miR-125b in HCC tumors for which one of them named eukaryotic translation initiation factor 5A2 (eIF5A2), known also as a liver oncofetal molecule, was validated to be a direct target of miR-125b in HCC.

Conclusions: This study has evidenced for the negative correlation of tumor miR-125b expression with poor prognosis of HCC patients. Expression of miR-125b can reverse the tumorigenic properties of cultured HCC cells via suppressing the tumorigenic molecule eIF5A2, thus postulating restoration of miR-125b level as a way to counteract liver tumorigenesis.